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Artful Dodger

Neven, in WX maps the number of isobars shows the pressure differential departing from standard SLP of 1013 mb. In the map above, the SLP at the center of the Beaufort High is over 1040 mb, a very strong system indeed.

Relative winds can be estimated from the distance between Isobars: the closer the lines, the faster the winds.

Wind direction is always parallel to the isobars. In the case of a High pressure system the circulation is Clockwise (when facing North), and Counter-clockwise for a Low Pressure system.

Now, after that brief interlude for WX 101 ...

In response to these winds, a large area of sea ice is moving south along a line from 165E-87N to 135W-75N. From Uni-Hamburg inter-day sea ice concentration maps, I estimate southward displacement over the last 19 hours at approx. 30 km. Also, there is a clockwise rotational component to the sea ice in the Beaufort and E. Siberian seas.

Neven

Artful, thanks for the explanation. Be sure to comment all of your thoughts, all of them, the coming week.

Did you compare this image to that image?

Artful Dodger

Not quite those. Uni-Hamburg issues 3 sea ice conc. maps per day, as follows:
(add a full minutes to the times below for the files to appear; these times are typical file timestamps from the FTP server)

At ~02:29 GMT, and again at ~21:37 GMT
ftp://ftp-projects.zmaw.de/seaice/NEAR_REAL_TIME/Arc_latest_large.png
- the 1st image of the day is overwritten and not retained
- the 2nd image of the day is retained and archived by month, in a folder named like this:
ftp://ftp-projects.zmaw.de/seaice/NEAR_REAL_TIME/201008/Arc/

Finally, there is a 3rd and separate map issued at ~14:31 GMT (named by date), here:
ftp://ftp-projects.zmaw.de/seaice/NEAR_REAL_TIME/201008/Central_Arctic/
This one is not overwritten, and is archived in the month's folder. It does have a different scale as the 2 other files, making it less useful for inter-day blink animations.

The blink animations are crack (you're been warned). I crop mine and watch my area of interest in glorious full hi-rez. Right now, you can really see the effect of wind on the ice edge and interior conc. distribution.

Altogether, the combination of these 3 images gives updated maps every 12+7+5 hours. I've got the last 14 days of the 02:30 'throw-away' maps. All the rest are publicly available on the FTP server.

Final note: file datetime stamps seem to be drifting forward slowly, perhaps with the satellite epoch or maybe sidereal time, I don't know.

Neven

Artful, you're amazing.

Artful Dodger

Please, call me "Lodger"... and i'm doing this left-handed!

Neven

That high-pressure system looks like it's going to vacuum clean McClure Strait free of ice in no time...

Artful Dodger

Yeah, I just checked the Canadian Ice Service website to see if they've declared the NW passage open yet. No new info. But with Prince of Wales Strait open to the East of Banks Island, and 4 Canadian Icebreakers in the area, and I consider it open for navigation now.

Lord Soth, can you enlighten us? Cheers!

Artful Dodger

Neven, your fries are ready: (file datetime stamp 08 02:36 GMT). Grab 'em before they're over-gone...

Lord Soth

Actually it is the Canadian Ice Service which is a branch of Environment Canada, which declares the North West Passage open or not. For them to declare the passage open,there would have to be less than 1/10 ice in at least one route thru the passage.

Since lives depend upon them; they wont declare the passage open until it is guaranteed clear sailing.

A lot of multiyear ice may filter down from the Northern Canadian Island into the passage, since the whole archipelago is fractured; and they may never declare the passage open; even if it is navigatiable with extreme care.

Artful Dodger

Thanks, Lord Soth. That answers another question that was raised here back in July: what percentage does the passage need to be declared open. Now we know it's 90%

Also, it appears that the IJIS SIE web page updater didn't fire properly tonight (even though the graphs are new, they're static links in the web page).

Still, the data table page was updated for Aug 7: now down -43,906 km^2 to 6,447,344 km^2.

siili

Talking about movement, not so much response from the buoys yet http://iabp.apl.washington.edu/maps_daily_arcticbasin.html some going away some staing put.

And how's the gridded data looking Lodger?

Artful Dodger

siili, I'm going to hold out for AMSR-E data. Should be a good winter coding project for a PS3 Cluster. Thanks for the links, though!

siili

OK, maybe then i can start with SSM/I and NASA Team and you do AMSR-E , do you prefere bootstrap or ASI or do you start directly with the feed?

But that last finger of old ice outside Banks Island must have a tough life, with the Healy reporting 8-9 degrees C water temperature, 1,5m waves and 25knots wind towards the coast.

Artful Dodger

Time & tide, siili... I'm hoping to get a good fit with a hindcast. Next Winter!

Hey, I thought you said your data analysis skills were rusty ;^)

siili

Now your talking like a true scientist, ice rheology, there shoiuld be large room for improvement, todays models appear a bit confused by the broken up ice of now.

I am rusty, but twenty years ago i did similar stuff for a living so hopefully with your encouregement i'll return.

Even if PIPS2 is a bit confused on the thickness of the ice, the forecasts on displacement looks much better, your southerly move is spreading towards the coast today.

If only that last bit of pink cloud south of Wrangel could disperse so we would get a true fix on the icearea.

Neven

Guys, I'm sorry I can't contribute to the heavy stuff (reached my limit when making that graph in OpenOffice Calc, hehe), but if you want space to divulge whatever it is you like to do: mi blog es su blog.

Artful Dodger

Neven, reality interlude -- Back before mid-June and the inception of this blog, did you have any reasonable notion that this melt season would evolve this way?

Neven

Lodger, I was thinking there might be a new record and thus I thought it might be a good idea to create a central place for people who want info on the melt.

My prediction has been from the start that if conditions would resemble those of 2007, there would be a new minimum extent record for sure. I'm not sure there will be a record now, but the lower this thing gets, the more obvious it will be that those 5-6 weeks of adverse atmospheric conditions have thwarted 2010's bid for the title.

I have learned a great deal in a short time, enough to see how complicated the whole thing is. It's utterly fascinating.

Artful Dodger

Truly.

Neven

Going to bed now, too late again. :-)

Anu

Just when your attention is drawn to a spectacular region of the Arctic (purple) and you start wondering... 250,000 sq km of melt coming in a day or so? 150,000? How big can a century-break get in August?

Out pops the mischievous Arctic goblin (red) for his annual one hour Summer appearance - now you see him, now you don't.

http://img713.imageshack.us/img713/9890/arclatestlargegoblin.png

Artful Dodger

Anu, at 07:00 GMT the Healy was steaming North at 71 11' N 139 38' W (water temp is 8.3 C). This position is 180 km from the US/Cda mainland Border, on a bearing of 020 True.

I make them about 20 to 22 km South of the Pack edge at 7 GMT (based on Uni-Bremen Pack edge at 02:30 GMT). If the Healy holds course & speed (12.6 knts), they'll cross into the main Ice Pack in about 1 hour. Since their tasking is to sonar map the Continental Shelf out to 300 NM, I expect they'll hold course. Speed should be interesting in the Ice (c.f. Amundsen/Barber 2009).

So, watch Healy's AloftCam after 08:00 GMTfor the first live image from the big show. Anxious to see the condition of the Ice from the surface... only a few minutes now.

siili

Maybe they decided to start with the D1 leg, when the ice is low there? http://continentalshelf.gov/missions/10arctic/background/media/TracklineJul10_3sm.pdf

siili

You have to work on your forecasting skills, i make it to only 7.6knots in the last hour, but i see it in the distance, they really should jack up the cadence on that cam. Tough wait for http://mgds.ldeo.columbia.edu/healy/reports/aloftcon/2010/20100808-0901.jpeg

Artful Dodger

Hey, I see 08:00 ice, Anu! Pretty good forecasting, Wot? ;^)

and BTW, your purple outline on Uni-Hamburg above is probably about 400,000 km^2.

http://www.gpsvisualizer.com/calculators

siili

Hopefully this will be the last time i'll ever see a pink cloud again, but it's such a good example to one finale time make my point. In the map two day ago http://www.iup.uni-bremen.de:8084/amsredata/asi_daygrid_swath/l1a/n6250/2010/aug/asi-n6250-20100806-v5_visual.png you see a small polynya at 135W 74N surrounded with high concentration ice, the next day this is transformed into a larger area of medium concentration ice http://www.iup.uni-bremen.de:8084/amsredata/asi_daygrid_swath/l1a/n6250/2010/aug/asi-n6250-20100806-v5_visual.png

This is not melt, wind or anything going on at the surface, this is the effect of dense clouds fooling the detector, making the map almost binary open water or 100% ice.
Probably an effect on the weather filters detecting bad weather and going to a lower resolution/longer wavelength mode with less detail.

The next day the clouds are gone, and the detecor sees what is really going on, uses the full resolution and gives us a glourious map.

Artful Dodger

yo, dude. you linked the same file twice. Besides, you'll need to compare an Ice conc. map to MODIS clouds to make this point. maybe as the clouds clear tomorrow you'll get your peek, but no pink elephants yet.

siili

Sorry my master, maybe you can change the last 6 into a 7? And indulge me in looking at the concurrent Aqua images, you'll see the cloud i promise!

In the water temperature dropped 7 degrees in 6 nautical miles travel for Healy!

Maybe you can circle the same areas in a microwave map and in an Aqua image Anu if you please?

My image is up in two minutes, got to go...

siili

The clouds did clear, that was my point. http://rapidfire.sci.gsfc.nasa.gov/subsets/?subset=Arctic_r05c02.2010218.aqua.1km http://rapidfire.sci.gsfc.nasa.gov/subsets/?subset=Arctic_r05c02.2010219.aqua.1km

Artful Dodger

Now we're in the main pack, on-board with Healy at 09:00

siili

Me like those meltponds...

siili

Looks like the Healy is right at the edge of Bremens old NP-37 tracking map http://www.iup.uni-bremen.de:8084/amsr/NP-37_visual.png maybe Neven should ask if they could replace that with one tracking Healy? Or even better since they have good relations to the Russians, make one of the Academic as well, and why not throw in the Chineese Snow Dragon as well, we could have a real summit at the top!

Artful Dodger

so siili, tell me what the winds were at 135W 74N during the period spanned by these two sea ice conc. maps. Hint: these maps show open water for any area with < 15 % concentration. This does not imply a polynya. It is an arbitary cutoff, for climate reporting purposes. Note the the Canadian Ice Service, with a different customer, showed in in Hudson's Bay well after all the Sea Ice Conc. maps has it as open water. These are not navigational charts.

siili

Not to different from now i suppose, judging from memory and ice displacement, but what has that to do with the main point? I agree on every word you write thereafter, we don't have to go to Hudson Bay to see differences this would be hard to deduce from Bremens map at least by me http://ice-glaces.ec.gc.ca/prods/WIS56CT/20100802180000_WIS56CT_0005118933.gif

Artful Dodger

I submit that the change in ice conc == ice displacement for this 24 hr period. Diffuse ice is moved easily by the wind.

I think the problem most comments expressed was difficultly understanding your novel combination of word choices: Pink + cloud. Clouds in the water? Which pink? Sometimes in science it's just better to stick with established nomenclature. I don't thing there are any relevant discovers to be made on the English communication side of this topic.

And now I'll sign off on this topic in the hopes that another commenter may have original input. I'm certain I've said all I can say. Good luck, and Keep watching the Sky!

Artful Dodger

Serious leads and broken floes at 10:00!

siili

Dear Lodger, i'm sorry my science communication skills are that miserable, just one final try before i sign off from this subject as well: Did you look at the two Aqua images i linked to? Did you spot any differences between them? If so, did you look at the passive microwave images from the same times and notice any differences between them at the same place?

A sharp edge in the icemap going into the NWP just by coincedence where a cloudboundary is? And the next day, no sharp edges at all ,just a very clear image of the ice, very nicely correlating with the optical image without clouds.

I'm sure this is a well known thing in the industry with a proper scientific name, I just don't know it, but i'd love to hear about it from anybody with knowledge.

Cheers Mate, and keep watching the ice while it lasts!

Artful Dodger

Good questions for someone with more expertise that I, siili. Cheers,

FrankD

Anu asked: How big can a century-break get in August?

In 9 years there have been 17 century breaks in August:
2003 - 3
2004 - 4
2007 - 4
2008 - 5
2010 - 1 (so far)

The biggest of those was 145,000 on 6/8/08. There has only been one century break after August 8th - 121,562 on 25 August 2008.

Anu

Wow, what a blizzard of interesting information...

I hadn't known about the Healy - those ice floes look wafer thin:
http://mgds.ldeo.columbia.edu/healy/reports/aloftcon/2010/20100808-1001.jpeg

Here's a nice map of the Healy's track - click on markers for ship data:
http://www.icefloe.net/cruisetrack.html

http://www.uscg.mil/pacarea/cgcHealy/
I'll have to look into this stuff to see what research the ship is up to.. Looks like I have to go read the "Healy thread".

FrankD - thanks for that century-break breakdown. 145,000 is pretty impressive ! PIOMAS is modelling some pretty thin ice - we'll see if record ocean temperatures meets record thin ice yields record century melts... Anyway, I expect much of the Beaufort/Chukchi/East-Siberian area Arctic Basin to be melted away by mid-September, I'm just wondering if we'll have a spectacular single day in there.

Siili - good questions about sensor confusion - yes, I imagine the clouds are the single hardest thing to handle with microwave data. I've tried to draw the MODIS square of one region of interest on the microwave map, so you can compare Arctic_r05c03 Subset images to the Arc_latest_large.png maps
See next post.

Anu

Siili,
here's the exact same area in a microwave map and the MODIS images:

http://img683.imageshack.us/img683/7821/arclatestlarge201008070.png
I just hand drew the red square based on the metadata for one region of interest:
http://rapidfire.sci.gsfc.nasa.gov/subsets/?subset=Arctic_r05c03.2010219.aqua.1km.met
(the lat/lon points for UpperLeft, UpperRight, LowerRight, LowerLeft)

This square is known as the Arctic_r05c03 Subset.

Here's the red and pink clouds in the Bands 3-6-7 image:
http://rapidfire.sci.gsfc.nasa.gov/subsets/?subset=Arctic_r05c03.2010219.terra.367.1km
Yes, the darker red areas seem to show the water/ice distinguished from clouds more clearly than in the TrueColor images.

I'd have to think about your notion of dense clouds fooling the algorithms some more - I haven't looked at the Bands 3-6-7 images too closely before...

Nick Barnes

I have been off the net for a couple of days, and have spent some of that time thinking about the consequences of the lower ice concentrations on the melt season and on arctic conditions generally.

The first thing to note is the obvious: diffuse ice - low concentrations and smaller floes - should melt more quickly. Ice melt is accelerated by increased contact with warmer open waters - which continually absorb heat and transport it to the edges and underside of the floes - and by wave action in the rougher seas which can develop when ice is diffuse. A consequence of this is that low-density areas (e.g. 30% ice) are historically rare: when local ice density drops below a certain level, most of the remaining ice melts quickly. This is why a normal density map is almost all either 90-100%, in the pack, or 0%, outside it.

Now this year - and to a lesser extent some other recent years - appear different. Huge swathes of the central ice area can't even properly be called a pack any more. We have another month or six weeks of melt season, with more than a million square kilometres - including, I estimate, most of the central ice between 135E and 135W, right up to the pole - below 80% concentration. I don't know why these areas haven't melted away, although the unusual wind and cloud conditions may account for it.

If much sun gets onto those waters (e.g. with the high-pressure area over the north Beaufort Sea), the water will warm and more of the ice will melt. Similarly, if the Gyre restarts (again, with that high), the ice should concentrate, which will cause extent falls.

This is why I expect large extent losses in the remaining melt season, and the season end to be later than average.

My other musing is on shipping and navigability. If the arctic ocean were 80% ice, all in one solid central pack, then one could sail or steam - in the open water around it - on auto-pilot. If the arctic ocean were 10% ice, in evenly-distributed 100-metre floes, one could not sail or steam in it at all (without either an icebreaker or nerves of steel). So the character of the ice - its density and concentration - is more important to navigability than the total area or extent. We can see this in the progress each year of the various amateur expeditions to sail the NWP or the NSR, or this year of Børge Ousland's to sail both in a single season. We can also see it on the webcam on USCGC Healy. Always, some areas which appear totally ice free on density maps - or even on 250m-resolution MODIS - contain some relatively small floes. Sometimes enough to make them dangerous, sometimes enough to make them impassable. This is one reason why this year I have stopped using the word "open" for the passages. Whether or not a passage is open is impossible to determine from a satellite instrument. We must rely on local experts, such as the Canadian Coast Guard.

siili

Thanks Anu for the pictures, what i have ment by a pink cloud, which in hindsight is not the best designation, is situated in the upper right corners of the square.

That very white area in the microwave image=high concentration of ice, is at the same place at what looks like a very opaqe cloud with no hints of ice/water below it. When i started to look at this i was a bit surprised that most clouds over the artic is not totally opaqe, you usually see something through them.

The opaqe pcs are usually situated over land, where one could guess that they are high clouds created by the greater energy over warming land, compared to the ice?

If I dare to suggest that you repeat your excersice for the next days pair of microwave/optical you will find that the 100% concentration white area is transformed into what you find over most of the other parts of the western arctic, more or less broken ice.

A slight complication, and other downside to the bad choise of pc, is that the microwave images AMSR-E is sitting on the Aqua satellite, not Terra which is the one with the infrared detector, and if the clouds move fast, the look between Aqua and Terra can be slightly different, another experiment perhaps.

I hope this is making some sense, i know i am challenged in my communication skills ,maybe you can become interpreter between Lodger and me, if you can follow us both?

siili

To be of the net souds like a good thing for the mind that i will try shortly, but my last day is not over yet, so i'll go on untill Neven stops me.

Very nice read Nick, that i probably will ruin by a little ramblings. The icepack indeed look very different this year from above, and if PIOMAS is anywhere near the truth that could be the reason for it, but anyway previous times with this look of the ice, was still on the outside in 2008, and then it was roughhandled by perfect storms that helped to take up all the energy.

What if, this year there are so much ice potentially meltable at the same time, but that the energy needed to do that just is not there? There has been little insolation when it matters, when the Sun is high in the sky, and now when we get clear skies, maybe the outgoing radiation is the greater than the incoming? And the open water areas just didn't get that much warming from the clouded Sun, so even the water can do much melting now?

And the inflows of warm water from the Atlantic and Pacific, just maybe there hasn't been that much of that either this year?

But think of the science in studing next melt season, when large parts of the arctic is made of Barbers, overgrown rotten ice, what will happen to that, if only the forcings are a little more like 2007 next year? We don't want to get to Maslowskis state three years ahead, do we?

Artful Dodger

The IJIS SIE revision for Aug 9 is -3125 km^2, daily change in SIE finalized at -50,313 km^2, for a total extent of 6,402,500 km^2.

Aug avg daily melt is now -64,941 km^2/day, and the 5-day moving avg is now -50,500.


JackTaylor

-
Artful Dodger @ 1627
The IJIS SIE revision for Aug 9 is -3125 km^2, daily change in SIE finalized at -50,313 km^2, for a total extent of 6,402,500 km^2.
Aug avg daily melt is now -64,941 km^2/day, and the 5-day moving avg is now -50,500.
-

Of interest to me is the revision for AUG-08 was the first one in a week with a downward revision:

08,02,2010,6731094
08,02,2010,6731250 (+)

08,03,2010,6651406
08,03,2010,6655000 (+)

08,04,2010,6572656
08,04,2010,6593281 (+)

08,05,2010,6525938
08,05,2010,6539375 (+)

08,06,2010,6478125
08,06,2010,6491250 (+)

08,07,2010,6447344
08,07,2010,6452813 (+)

08,08,2010,6405625
08,08,2010,6402500 (-)

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